A range of molecular technologies for the detection of a target analyte in a sample have been developed. Such methods have application in, for example, public health, the detection of pathogens in food or water, epidemiological studies, genetically modified organism (GMO) detection, medicine, clinical diagnoses, disease susceptibility diagnoses, tissue typing, blood screening, forensic medicine, bioweapon detection, molecular toxicology, gene therapy, and DNA tagging, among many other applications.
Current methods for detecting an analyte such as a nucleic acid generally involve one, or a combination of, molecular techniques. These techniques generally fall into three groups loosely defined as sequence-specific detection, sequence-specific enrichment and signal amplification.
Most detection techniques gain their sequence specificity through base pairing of complementary probes or oligonucleotides to a sequence of interest within the target DNA sample.
The two most commonly used DNA detection methods, namely the polymerase chain reaction (PCR) and Southern blotting, differ in how they proceed from this point. The PCR method enriches a target DNA through a series of amplification cycles and signal detection can be, for example, through the use of stains, fluorescence or radiolabeling.
Southern blotting involves no DNA enrichment step, but uses high-energy 32P for signal amplification. These extensively used techniques, although highly developed, still retain significant drawbacks. For PCR, the equipment required is expensive, the process is time-consuming and the degree of expertise required is high. Southern blotting often uses hazardous radioactive labeling, takes up to a week to complete, and requires large amounts of substrate DNA.
Reverse transcription polymerase chain reaction (RT-PCR) is a laboratory technique commonly used in molecular biology, which enables for the analysis of genes expressed from template DNA in cells. In RT-PCR, an RNA strand is first reverse transcribed into its DNA complement (complementary DNA, or cDNA) using the enzyme reverse transcriptase, and the resulting cDNA is amplified using conventional or real-time PCR. This approach is widely used to detect the expression of a gene or gene(s) in a given sample, and replaces the traditional Northern Blotting method. As described above, the laboratory equipment and reagents required for RT-PCR is expensive, the process is time-consuming and require a high degree of scientific training.
In light of the above, further methods for detecting analytes such as nucleic acids which are target-specific and sensitive would be desirable.
Reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that this prior art forms part of the common general knowledge in any country.